This invention relates to movable stands for vertical pole support comprising a base container and a detachable lid, which may be filled with ballast material, in particular, but not necessarily, for stressful applications such as for games having a vertical pole of the tether-ball type, such as the tether tennis game known as xe2x80x9cSWINGBALLxe2x80x9d (Trade Mark) or the tethered soccer-ball game known as xe2x80x9cSOCCER SWINGBALLxe2x80x9d (Trade Mark), where the pole held by the stand may be subjected to violent shocks and pressures during the playing of such games. The stand may also conveniently be used for other sporting activities such as basketball, or other applications such as for holding umbrella poles.
In describing a stand as movable, this refers to the feature that such stands are not normally immovably fixed or positively anchored to the ground. When not filled with ballast, the stand is light and easily transportable. When filled with ballast, while providing stable support for a pole, it will still be practical to move the base from one location to another.
Tether tennis type games, such as xe2x80x9cSWINGBALLxe2x80x9d (Trade Mark), include a pole which traditionally has been anchored by forcing the lower end vertically directly into the ground, which is facilitated by a pointed lower end of the pole. The pole has a helical anchoring device at its upper end and a tennis type ball is tethered to this by a cord.
The game is played by the striking of the ball with racquets or paddles by opponents in opposite directions around the pole, causing the attachment of the line to the helix to rise up or down the helix.
The tethered soccer-ball game xe2x80x9cSOCCER SWINGBALLxe2x80x9d (Trade Mark), is similar to SWINGBALL (Trade Mark), except that the ball is substantially larger and heavier, of the football or soccer ball type, and the pole is shorter, so that the football may be kicked around the pole at ground level.
It will be appreciated that considerable stress can be transferred to the pole during play of games of this type and if the pole is anchored in soft ground, it has been found that the pole soon becomes loose. It will also be appreciated that it will not be possible to play games of this type where the pole is unable to be inserted into hard soil, or where the game is required to be played on any other type of hard surface which the pole end cannot penetrate.
Games of the tether tennis type have been marketed for many years and an on-going search has been mounted for a suitable stand to enable such games to be played on hard surfaces, where it is not possible to force the point of the pole into the ground, or where the ground is too soft to hold the pole firmly upright during play.
One of the main problems is that a suitable stand for games of this type has to be extremely robust to withstand the pressures and shocks which have to be absorbed by the stand during play.
One type of stand which has been tried for use with tetherball type games is the blow-moulded plastic beach umbrella stand. Typically these weigh about 2 to 4 pounds (approximately 1 to 2 kilograms) when empty, are blow-moulded in high density polyethylene plastic and have a filler hole on the top through which water, as ballast material, can be poured in, or out.
These stands normally have a capacity of about 0.5 to 1 cubic feet (approximately 15 to 25 liters), cover a surface area of about 1.5xc3x971.5 feet (approximately 0.5xc3x970.5 meters) and weigh about 30 to 50 pounds (approximately 15 to 25 kilograms) when filled with water as ballast material and are fitted with a central internal socket and clamping means to receive and hold the bottom end of a beach umbrella pole therein.
One of the problems with the use of blow-moulded stands of this type for tetherball games, is that the blow-moulding process distributes a layer of plastic material of uniform thickness over the surface of the mould, resulting in a reasonably uniform wall thickness of the stand. This makes it difficult to provide for localized thickened sections, so as to reinforce areas subject to particularly high stresses during play, such as the socket and the area adjacent, which holds the bottom end of the pole, or the area of the upper surface adjacent to the pole. After extended play stands of this type tend to rupture or split in these areas and are therefore unsuitable for use with tetherball games.
Blow-moulded stands are also bulky to store and transport, and while ballast material such as water may be added or removed through a filler hole, it is more laborious with sand or gravel, and, depending on the size of the filler hole (which may not be so big so as to compromise the structural integrity of the stand) virtually impossible to use large objects such as bricks or stones as ballast material.
An attempt to obviate the problem of bulkiness of stands for garden umbrellas has been made in U.S. Pat. No. 4,591,126 (Sheldon Berney), which provides for a base or stand having a base section and a separate lid portion.
This lid is designed to inter-connect to the base by a peripheral continuous snap sealing means of the tongue and groove type. However, no reference is made to any need to remove the lid from the base having been assembled, and in particular, no reference is made to the ease of removing the lid in terms of the pressure required to unlock the snap fit. This invention does not refer to the requirements of stressful applications, such as games of the tether tennis type, that the lid remain attached to the base during play, and also be easily detachable by young children, or that the seal between lid and base be effective for the containment of ballast material during such use.
A different type of stand, which did attempt to address the requirements of tetherball games, is described in U.S. Pat. No. 4,148,455. The stand in this patent comprises a base container for water or sand or other ballast, and has a formation for receiving the bottom end of the pole.
The removable lid has an orifice with formations, which co-act with a foot plate on the pole, so as to prevent rotation of the pole. There is however, no detailed reference or description of the peripheral sealing arrangement between lid and base in this patent. The problem with the design of this stand is that the lid is described as being xe2x80x9ceasily snapped in and out of placexe2x80x9d (lines 42 and 43 of column two of U.S. Pat. No. 4,148,455).
There is no positive locking arrangement for the lid and base container apart from this xe2x80x9csnapxe2x80x9d action and under the pressure of shocks exerted in stressful applications such as the playing of tether ball games, the snap seal between the lid and the base can break loose allowing water ballast to spill freely out of the base container or even for the lid to become completely unseated from the base container. Because of this design defect, the stand is unsuitable for stressful applications such as tether ball type games and a stand according to U.S. Pat. No. 4,148,455 as far as is known has never been made available commercially.
As a general comment, as well as in referring to the above U.S. Pat. Nos. 4,591,126 and 4,148,455, it should perhaps be noted that when assessing the suitability of the design of stands for poles for use in stressful applications which have removable lids, and where such lids are designed to engage the base container with a xe2x80x9csnapxe2x80x9d fit, that snap sealing means of this type face the contradictory requirements of providing a strong attachment of the lid to the base, together with a contrasting need in applications such as envisaged in this patent application, for the joint to be easily releasable by young children.
In general therefore, a lid which engages with a releasable snap fit to a base container is not suitable for the applications envisaged by this patent application.
It is an object of this present invention to provide a robust movable stand for vertical pole support having a rigid, or semi-rigid, base container component and an easily detachable lid component, which will hold a pole in its mounted position, particularly for use in conjunction with stressful applications such as for games of the tether ball type, which will resist the violent jerks encountered during the play of these games, without the lid becoming free of the base container, and which will also maintain an effective seal between the lid and base container, so as to prevent the escape of water or other types of ballast through this joint during play.
It will be appreciated that this stand may also conveniently be used as apparatus for other sporting activities such as basketball, or for holding umbrella poles, or other applications, even though the shocks and pressures in these applications may not be as onerous as for games of the tetherball type.
According to the present invention, a movable stand is provided for vertical pole support in which the lid and base container components are attached together by a two stage attachment system which, in combination, provide an effective attachment between the lid and base container for use in stressful applications such as for games of the tetherball type as described previously.
The lid and container are rigid or semi-rigid, and preferably moulded from plastic materials. In addition, locking or clamping means may be provided to positively secure any pole which is mounted in the stand, so that the pole is unable to pull free from its mounted position in the stand, unless such locking means are released.
The primary attachment means between the lid and the base components consists of a complemental inter-engageable tongue and groove formation, in which the tongue member, of little width compared with its height in cross section, located around the periphery of the one component, fits into and is there enveloped and held closely by the groove at the periphery of the other component.
This primary attachment means implements an effective seal between the lid and base container which prevents water or other ballast from leaking out through the joint, should the base container be shaken or jolted, as can occur during play of games of the tetherball type.
An important aspect of this tongue and groove design is that at all points of this joint around the peripheries of the base container and lid, the tongue is held on both sides by the groove so as to resist at any point displacement of the lid relative to the base by shocks or jolts from either side which might be imparted during play of games of the tetherball type.